Raw (format)
The raw image format (understood as "raw" or "raw" following the Anglo-Saxon term to refer to camera raw) is a digital image file format that contains all of the image data as it has been captured by the camera's digital sensor, whether photographic or otherwise.
Main features
Type of compression
The raw format generally has lossless data compression applied to it.
Color Depth
Because it contains the full data of the image captured by the camera and a higher color depth (typically 36 to 48 bits/pixel), its files have a very large file size, despite which generally use compression.
Professional and semi-professional cameras generally offer the option of recording images in this format, as well as JPG and eventually others. Also some high-end compact cameras offer this possibility.
Different versions of the format
The big drawback of this format is the lack of standardization: each camera manufacturer uses its own version of the format, which can lead to incompatibilities or that version of raw cannot be used in the future. The OpenRAW initiative works for camera manufacturers to create an open source and standard raw format. Another open source alternative is Adobe's Digital Negative Format, or DNG.
Utility and common uses
Later fixes
If we shoot two photos of the same subject, one in JPG with low data compression (high quality) and another in raw, surely the one taken in jpg will look better: it will have better sharpness/focus, better contrast, better lighting and colors will appear better represented. This is because a digital camera often applies different digital filters to enhance the image. However, the raw format shows us the photo as the sensor captured it, without any enhancement filter. You will see more neutral, less saturated colors, a softer focus and a lighting that will depend on the exposure we did, more visibly over or underexposed if that were the case. However, a jpg photo, being in RGB mode, has 24 bits/pixel (8 per channel) compared to the 30 to 48 bits/pixel (10 to 16 per channel) that the image obtained when developing the file usually contains. raw. The 24 bits of RGB will be enough to see the full range of possible colors, but it will be clearly insufficient when we want to make certain adjustments to the image (lighting, tonal correction, etc.).
On the other hand, an image in raw format, although it may appear poorer, contains much more information and can be easily manipulated by adjusting lights and colors. Compared to JPG, the problem is its size, since it occupies significantly more than its jpeg equivalent. Compared to lossless data compression file formats like TIF or PNG, the problem boils down to the need to "reveal it" before it can be processed normally for any use.
Digital negative
The raw files are also known as digital negatives, although this simile is not entirely correct since, being the RAW of a digital file, it can be replicated as many times as desired and, with computer knowledge necessary, alter its content.
Software for viewing and processing raw files
Preview, Open and Convert
Cameras that support raw files usually come with their own software for converting raw to other formats such as TIFF or JPEG. Other conversion programs and plug-ins are available from vendors who have licensed the technology from the camera manufacturer, although converters have also been reverse-engineered to display images in some specific raw formats.. A portable open source program is dcraw, which supports the raw format and can run on various operating systems but was not supported by camera manufacturers.
In 2004, Adobe Systems published the Digital Negative Specification (DNG), which is intended to be a unified raw format. Adobe Photoshop CS2 and CS3 contain extensive support for raw in Adobe Photoshop Lightroom software. Starting in 2006, several camera manufacturers have begun to announce support for DNG in newer camera models, including Leica, Samsung, Ricoh, Pentax, and Hasselblad. The Leica Digital-Modul-R (DMR) was the first to use its DNG as its native format.
For Windows XP, a free download is available that integrates viewing and printing of photos included in other programs, but is not supported by Microsoft. In addition, Windows Photo Gallery and Windows Live can view any format raw image if WIC codecs are installed. Camera manufacturers such as Canon, Nikon, Sony, Olympus, and Pentax have released WIC codecs. Commercial DNG codecs are also available from Ardfry Imaging.
In Linux, for both KDE and Gnome, the two major desktop environments, there are numerous plugins that allow direct viewing of raw images from their default file managers, Dolphin and Nautilus respectively, as well as from viewer programs and image catalogers like Gwenview or Digikam.
In 2005, Apple Computer introduced several products that offer raw file support, such as iPhoto 5, which offered basic support for viewing and editing raw files. The new version of its operating system, Mac OS X 10.4, added raw support directly to the operating system, as part of the ImageIO environment, which automatically adds raw support to most of Mac OS X applications, both from Apple (such as the preview, Mac OS X is PDF and opener and image viewing application, a post-production photo software package for professionals), as well as all third-party applications that make use of the ImageIO frameworks. Semi-regular updates to OS X generally include support for newer raw file formats introduced by camera manufacturers.
The IrfanView software is capable of handling this type of images, as long as the necessary plug-ins are added; both software and plug-ins are free, for personal use.
Raw processing or development
There are many other applications for "rawdevelopment" or "workflow in raw" designed to provide processing and post-production of raw images, before being exported in another format such as TIF or JPG.
Among the free tools, the best known is UFRaw, free software based on dcraw that it can work as a GIMP plugin and is available for most operating systems; also darktable, which is capable of managing a large number of images; RawShooter Essentials 2005 / 6, free software developed by Pixmantec; other "rawdevelopment alternatives" free based on dcraw are RawStudio or RawTherapee, free since its version 3.
In the field of proprietary paid programs, Helicon Filter, Phase One Capture One and Bibble Labs' Bibble Pro, as well as Apple's Aperture, Adobe Photoshop, Adobe Photoshop Lightroom, and PhotoLine.
All of these programs provide sophisticated controls for processing the information stored in the raw file and for converting raw files to JPEG or TIFF format, but others such as Picasa, Google's cataloging and image editing program, or Apple's iPhoto, can also read and display many raw formats, although they offer only limited tools for processing these files.
In 2006, Adobe Systems Inc acquired the rights from Pixmantec ApS. RawShooter Essentials will not be updated (the latest update adds support for the Canon 5D and Nikon D200). Adobe Photoshop Lightroom up to version 1.0, which was released in March 2007, can still be downloaded for free. The software comes complete, including support for various raw formats, conversion to other formats and batch processing. LightZone is an image editing program that offers the ability to edit raw natively. Most tools convert raw before they can process it, but LightZone allows users to edit raw as if it were TIFF or JPEG.
Bibliography Cited
Carrasco, Jorge (2010). Cinema and digital television. Technical Manual. Barcelona: Editions of the University of Barcelona. ISBN 978-84-475-3457-9.